/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.wal.utils;

import java.io.File;
import java.util.Arrays;
import java.util.Comparator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static org.apache.iotdb.commons.conf.IoTDBConstant.*;

public class WALFileUtils {
    /**
     * versionId is a self-incremented id number, helping to maintain the order of wal files.
     * startSearchIndex is the valid search index of last flushed wal entry. statusCode is the. For
     * example: <br>
     * _0-0-1.wal: 1, 2, 3, -1, -1, 4, 5, -1 <br>
     * _1-5-0.wal: -1, -1, -1, -1 <br>
     * _2-5-1.wal: 6, 7, 8, 9, -1, -1, -1, 10, 11, -1, 12, 12 <br>
     * _3-12-1.wal: 12, 12, 12, 12, 12 <br>
     * _4-12-1.wal: 12, 13, 14, 15, 16, -1 <br>
     */
    public static final Pattern WAL_FILE_NAME_PATTERN =
            Pattern.compile(
                    String.format(
                            "%s(?<%s>\\d+)-(?<%s>\\d+)-(?<%s>\\d+)\\%s$",
                            WAL_FILE_PREFIX,
                            WAL_VERSION_ID,
                            WAL_START_SEARCH_INDEX,
                            WAL_STATUS_CODE,
                            WAL_FILE_SUFFIX));

    public static final String WAL_FILE_NAME_FORMAT =
            WAL_FILE_PREFIX
                    + "%d"
                    + FILE_NAME_SEPARATOR
                    + "%d"
                    + FILE_NAME_SEPARATOR
                    + "%d"
                    + WAL_FILE_SUFFIX;

    /**
     * Return true when this file is .wal file
     */
    public static boolean walFilenameFilter(File dir, String name) {
        return WAL_FILE_NAME_PATTERN.matcher(name).find();
    }

    /**
     * List all .wal files in the directory
     */
    public static File[] listAllWALFiles(File dir) {
        return dir.listFiles(WALFileUtils::walFilenameFilter);
    }

    /**
     * Parse version id from filename
     */
    public static long parseVersionId(String filename) {
        Matcher matcher = WAL_FILE_NAME_PATTERN.matcher(filename);
        if (matcher.find()) {
            return Long.parseLong(matcher.group(WAL_VERSION_ID));
        }
        throw new RuntimeException("Invalid wal file name: " + filename);
    }

    /**
     * Parse start search index from filename
     */
    public static long parseStartSearchIndex(String filename) {
        Matcher matcher = WAL_FILE_NAME_PATTERN.matcher(filename);
        if (matcher.find()) {
            return Long.parseLong(matcher.group(WAL_START_SEARCH_INDEX));
        }
        throw new RuntimeException("Invalid wal file name: " + filename);
    }

    /**
     * Parse status code from filename
     */
    public static WALFileStatus parseStatusCode(String filename) {
        Matcher matcher = WAL_FILE_NAME_PATTERN.matcher(filename);
        if (matcher.find()) {
            return WALFileStatus.valueOf(Integer.parseInt(matcher.group(WAL_STATUS_CODE)));
        }
        throw new RuntimeException("Invalid wal file name: " + filename);
    }

    /**
     * Sort wal files by version id with ascending order
     */
    public static void ascSortByVersionId(File[] walFiles) {
        Arrays.sort(walFiles, Comparator.comparingLong(file -> parseVersionId(file.getName())));
    }

    /**
     * Find index of the file which probably contains target insert plan. <br>
     * Given wal files [ _0-0-1.wal, _1-5-0.wal, _2-5-1.wal, _3-12-1.wal, _4-12-1.wal ], details as
     * below: <br>
     * _0-0-1.wal: 1, 2, 3, -1, -1, 4, 5, -1 <br>
     * _1-5-0.wal: -1, -1, -1, -1 <br>
     * _2-5-1.wal: 6, 7, 8, 9, -1, -1, -1, 10, 11, -1, 12, 12 <br>
     * _3-12-1.wal: 12, 12, 12, 12, 12 <br>
     * _4-12-1.wal: 12, 13, 14, 15, 16, -1 <br>
     * searching [1, 5] will return 0, searching [6, 12] will return 1, search [13, infinity) will
     * return 3， others will return -1
     *
     * @param files             files to be searched
     * @param targetSearchIndex search index of target insert plan
     * @return index of the file which probably contains target insert plan , -1 if the target insert
     * plan definitely doesn't exist
     */
    public static int binarySearchFileBySearchIndex(File[] files, long targetSearchIndex) {
        if (files == null
                || files.length == 0
                || targetSearchIndex <= parseStartSearchIndex(files[0].getName())) {
            return -1;
        }

        if (targetSearchIndex > parseStartSearchIndex(files[files.length - 1].getName())) {
            return files.length - 1;
        }

        int low = 0;
        int high = files.length - 1;
        // search file whose search index i < targetSearchIndex
        while (low <= high) {
            int mid = (low + high) >>> 1;
            long midVal = parseStartSearchIndex(files[mid].getName());

            if (midVal < targetSearchIndex) {
                low = mid + 1;
            } else {
                high = mid - 1;
            }
        }

        return low - 1;
    }

    /**
     * Get .wal filename
     */
    public static String getLogFileName(long versionId, long startSearchIndex, WALFileStatus status) {
        return String.format(WAL_FILE_NAME_FORMAT, versionId, startSearchIndex, status.getCode());
    }
}
